Method and device for determining the concentration of an analyte using fluorescence measurement

Abstract

A method is presented for determining the concentration of an analyte in a liquid sample using a reagent system. The reaction of the sample with the reagent system results in a change of the quantity of a fluorophore, the quantity of the fluorophore correlating with the concentration of the analyte, a characteristic measurement variable for the quantity of the fluorophore being measured, and the concentration of the analyte being determined using an evaluation algorithm on the basis of the measurement variable. The reagent system is integrated in an analysis system and the fluorescence lifetime of the fluorophore is used in the ascertainment of the concentration of the analyte.

1 . A method for determining the concentration of glucose in a liquid sample using a reagent system which contains glucose dehydrogenase (GlucDH), comprising:
 (a) providing an analysis element in which the reagent system is operatively integrated;   (b) reacting the sample with the reagent system in order to produce a change of the quantity of a fluorophore, the fluorophore being selected from the group comprising NADH/H +  and NADPH/H + , including their derivatives, wherein the quantity of the fluorophore correlates with the concentration of the analyte and wherein the reaction of the sample with the reagent system includes a complex formation with participation of the GlucDH and the fluorophore;   (c) measuring a measurement variable which is characteristic for the quantity of the fluorophore; and   (d) determining the concentration of the analyte on the basis of the measurement variable using an evaluation algorithm;   
     wherein fluorescence lifetime of the fluorophore is used in the determining the concentration of the analyte. 
   
   
       2 . The method according to  claim 1 , wherein the fluorophore is a derivative of NADH/H +  or NADPH/H + , whose pyridine ring is not modified or is carbaNAD. 
   
   
       3 . The method according to  claim 1 , wherein the fluorescence lifetime of the fluorophore is used in the evaluation algorithm as the measurement variable which is characteristic for the concentration. 
   
   
       4 . The method according to  claim 1 , wherein the measured fluorescence lifetime is used in the evaluation algorithm in combination with an other measurement variable which is characteristic for the concentration, wherein the other measurement variable comprises fluorescence intensity. 
   
   
       5 . The method according to  claim 4 , wherein the measured fluorescence lifetime is used in the evaluation algorithm to compensate for measurement errors which are caused by interfering variables. 
   
   
       6 . The method according to  claim 1 , wherein the measurement of the fluorescence lifetime is used to determine a lifetime-related value of the fluorescence intensity. 
   
   
       7 . The method according to  claim 6 , wherein the fluorescence intensity is measured for at least two different fluorescence lifetimes in order to determine in each case lifetime-related values of the fluorescence intensity. 
   
   
       8 . The method according to  claim 7 , wherein the two lifetime-related values of the fluorescence intensity are related to one another. 
   
   
       9 . An analysis system for determining the concentration of an analyte in a liquid sample, the system comprising a reagent system containing glucose dehydrogenase (GlucDH), whose reaction with the sample results in a change of the quantity of a fluorophore, the fluorophore comprising one of NADH/H +  and NADPH/H +  including their derivatives, the quantity of the fluorophore correlating with the concentration of the analyte, the reaction of the sample with the reagent system including a complex formation with participation of the GlucDH and the fluorophore, and an evaluation instrument comprising a measuring unit for measuring a measurement variable which is characteristic for the quantity of the fluorophore, and an evaluation unit for determining the concentration of the analyte on the basis of the measurement variable, using an evaluation algorithm, wherein the reagent system comprises reagents contained in dry form in an analysis element, and wherein the measuring unit of the evaluation instrument is adapted for measuring and/or taking into account the fluorescence lifetime of the fluorophore.